MARIA/MARY THE JEWESS, founder of a school of alchemy in Egypt 1st -2nd century AD. She studied sulphur compounds and was believed to have created a process for making silver sulphide, a matte-black compound usable for metalwork inlays. Similar to what artists now call niello. Maria was the equivalent of an industrial chemist more than an alchemist. It is believed that she made various designs of stills and condensers for working with hot metals and vapours. The main item now associated with her is the Bain-Marie (Maria’s bath), as used in cooking. A simple double boiler, but one which she used for boiling mercury or sulphur and then using the condensing vapours to heat copper or lead in a pan above. The whole process was at a high temperature. This device was probably the first prototype of autoclaves and pressure cookers. It is a sad reflection on her memory that the French have a term ‘Femme au Bain-Marie’, slang for an empty-headed woman. Also known as Miriam the Alchemist, the Prophetess.